WPW Syndrome–Wolff-Parkinson-White Syndrome

Wolff Parkinson White syndrome

Background

In 1930, Wolff, Parkinson, and White described a series of young patients who had a bundle branch block pattern on electrocardiography (ECG) findings, a short PR interval, and paroxysms of tachycardia.  Case reports began appearing in the literature in the late 1930s and early 1940s, and the term Wolff-Parkinson-White (WPW) syndrome was coined in 1940.

Preexcitation was defined by Durrer et al in 1970 with the following statement, "Preexcitation exists, if in relation to atrial events, the whole or some part of the ventricular muscle is activated earlier by the impulse originating from the atrium than would be expected if the impulse reached the ventricles by way of the normal specific conduction system only."

WPW syndrome is currently defined as a congenital abnormality involving the presence of abnormal conductive tissue between the atria and the ventricles in association with supraventricular tachycardia (SVT).  It involves preexcitation, which occurs because of conduction of an atrial impulse not by means of the normal conduction system, but via an extra atrioventricular (AV) muscular connection, termed an accessory pathway (AP), that bypasses the AV node.

Classic ECG findings that are associated with WPW syndrome include the following:

• Presence of a short PR interval (< 120 ms)
• A wide QRS complex longer than 120 ms with a slurred onset of the QRS waveform producing a delta wave in the early part of QRS
• Secondary ST-T wave changes     Classic Wolff-Parkinson-White electrocardiogram with short PR, QRS >120 ms, and delta wave.

Patients with WPW syndrome are potentially at an increased risk of dangerous ventricular arrhythmias due to extremely fast conduction across the bypass tract if they develop atrial flutter or atrial fibrillation (AF).

Some patients have a concealed bypass tract.  Although they have an accessory AV connection, it lacks antegrade conduction;  accordingly, these patients do not have the classic abnormalities of the surface ECG.

Only a small percentage of patients with WPW syndrome (< 1%) are at risk for sudden cardiac death (SCD). In patients who present with pre -excited AF, cardiac electrophysiologic studies and radiofrequency (RF) catheter ablation may be curative.  Other presentations include symptomatic SVT, which can also be cured by catheter ablation.  Asymptomatic patients need periodic observation.  The onset of cardiac arrhythmias, and possibly the sudden death risk, may be eliminated by prophylactic catheter ablation as well.

Your treatment may include several options.

• Cardioversion.  In cardioversion, your doctor may use paddles or patches on your chest to electrically shock your heart and help restore your heart's normal rhythm.  Doctors also may use drugs to stop your heart's fast rhythm and restore a normal rhythm.
• Catheter radio frequency ablation.  In catheter radio frequency ablation, your doctor inserts thin, flexible tubes (catheters) in a blood vessel in your arm or groin and threads them through your blood vessels to your heart.  Your doctor then applies heat (radiofrequency energy) or extreme cold (cryoablation) through the catheter to destroy (ablate) the extra electrical pathway causing your condition.
• Surgery.  If other treatment is not effective, your doctor rarely may perform open-heart surgery to destroy the extra electrical pathway causing your condition.
• Medications.  Your doctor may prescribe medications to control your heart rate or heart rhythm.
• Follow-up care and monitoring.  Follow-up appointments with your doctor to monitor your heart rhythm and rate.  If you are not experiencing any symptoms, you may require only monitoring of your condition.

Wolff-Parkinson-White syndrome is a condition characterized by abnormal electrical pathways in the heart that cause a disruption of the heart's normal rhythm (arrhythmia).

The heartbeat is controlled by electrical signals that move through the heart in a highly coordinated way.  A specialized cluster of cells called the atrioventricular node conducts electrical impulses from the heart's upper chambers (the atria) to the lower chambers (the ventricles).  Impulses move through the atrioventricular node during each heartbeat, stimulating the ventricles to contract slightly later than the atria.

What are the symptoms of Wolff Parkinson White syndrome

People with Wolff-Parkinson-White syndrome are born with an extra connection in the heart, called an accessory pathway, that allows electrical signals to bypass the atrioventricular node and move from the atria to the ventricles faster than usual.  The accessory pathway may also transmit electrical impulses abnormally from the ventricles back to the atria.  This extra connection can disrupt the coordinated movement of electrical signals through the heart, leading to an abnormally fast heartbeat (tachycardia) and other arrhythmias.  Resulting symptoms include dizziness, a sensation of fluttering or pounding in the chest (palpitations), shortness of breath, and fainting (syncope).  In rare cases, arrhythmias associated with Wolff-Parkinson-White syndrome can lead to cardiac arrest and sudden death.  The most common arrhythmia associated with Wolff-Parkinson-White syndrome is called paroxysmal supraventricular tachycardia.

Symptoms:

How common is Wolff-Parkinson-White syndrome?
Wolff-Parkinson-White syndrome affects 1 to 3 in 1,000 people worldwide.  Only a small fraction of these cases appear to run in families. Wolff-Parkinson-White syndrome is a common cause of an arrhythmia known as paroxysmal supraventricular tachycardia.  Wolff-Parkinson-White syndrome is the most frequent cause of this abnormal heart rhythm in the Chinese population, where it is responsible for more than 70 percent of cases.

What genes are related to Wolff-Parkinson-White syndrome?
Mutations in the PRKAG2 gene cause Wolff-Parkinson-White syndrome. A small percentage of all cases of Wolff-Parkinson-White syndrome are caused by mutations in the PRKAG2 gene.  Some people with these mutations also have features of hypertrophic cardiomyopathy, a form of heart disease that enlarges and weakens the heart (cardiac) muscle.  The PRKAG2 gene provides instructions for making a protein that is part of anenzyme called AMP-activated protein kinase (AMPK). This enzyme helps sense and respond to energy demands within cells.  It is likely involved in the development of the heart before birth, although its role in this process is unknown.

Researchers are uncertain how PRKAG2 mutations lead to the development of Wolff-Parkinson-White syndrome and related heart abnormalities.  Research suggests that these mutations alter the activity of AMP-activated protein kinase in the heart, although it is unclear whether the genetic changes overactivate the enzyme or reduce its activity.  Studies indicate that changes in AMP-activated protein kinase activity allow a complex sugar called glycogen to build up abnormally within cardiac muscle cells.  Other studies have found that altered AMP-activated protein kinase activity is related to changes in the regulation of certain ion channels in the heart.  These channels, which transport positively charged atoms (ions) into and out of cardiac muscle cells, play critical roles in maintaining the heart's normal rhythm.

In most cases, the cause of Wolff-Parkinson-White syndrome is unknown.

Most cases of Wolff-Parkinson-White syndrome occur in people with no apparent family history of the condition. These cases are described as sporadic and are not inherited. Familial Wolff-Parkinson-White syndrome accounts for only a small percentage of all cases of this condition.  The familial form of the disorder typically has an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the condition.  In most cases, a person with familial Wolff-Parkinson-White syndrome has inherited the condition from an affected parent.

What other names do people use for Wolff-Parkinson-White syndrome?
1. Ventricular pre-excitation with arrhythmia
2. WPW Syndrome

Drugs and Medications used to treat Wolf-Parkinson-White syndrome:
Note:  You must always seek professional medical advice about any prescription drug, OTC drug, medication, treatment or change in treatment plans.

Some of the different medications used in the treatment of Wolf-Parkinson-White syndrome include:

Complications of Wolff-Parkinson-White syndrome can occur at any age, although some individuals born with an accessory pathway in the heart never experience any health problems associated with the condition.

Complications of Wolf-Parkinson-White syndrome may include:

Wolff-Parkinson-White syndrome often occurs with other structural abnormalities of the heart or underlying heart disease.  The most common heart defect associated with the condition is Ebstein anomaly, which affects the valve that allows blood to flow from the right atrium to the right ventricle (the tricuspid valve).  Additionally, Wolff-Parkinson-White syndrome can be a component of several other genetic syndromes, including: hypokalemic periodicparalysis (a condition that causes episodes of extreme muscle weakness), Pompe disease (a disorder characterized by the storage of excess glycogen), and tuberous sclerosis (a condition that results in the growth of noncancerous tumors in many parts of the body).

Prognosis of  Wolff-Parkinson-White syndrome:  usually benign but can be very serious in some cases.

References

1. Early et al. Wolff-Parkinson-White Syndrome. In: Ferri FF. Ferri's Clinical Advisor 2011: Instant Diagnosis and Treatment. Philadelphia, Pa.: Mosby Elsevier; 2011. http://www.mdconsult.com/books/page.do?sid=1087785533&eid=4-u1.0-B978-0-323-05610-6..00032-9--sc29000&isbn=978-0-323-05610-6&type=bookPage§ionEid=4-u1.0-B978-0-323-05610-6..00032-9--sc29000&uniqId=227936882-3. Accessed Nov. 24, 2010.
2. Wolff-Parkinson-White Syndrome. American Heart Association. http://www.americanheart.org/presenter.jhtml?identifier=4785. Accessed Nov. 24, 2010.
3. Arnsdorf MF, et al. Epidemiology of the Wolff-Parkinson-White syndrome. http://www.uptodate.com/home/index.html. Accessed Nov. 24, 2010.
4. Wolff-Parkinson-White (WPW) Syndrome. The Merck Manuals: Home Edition for Patients and Caregivers. http://www.merckmanuals.com/home/sec03/ch027/ch027e.html. Accessed Nov. 24, 2010.
5. Wolff-Parkinson-White Syndrome. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/wolff-parkinson-white-syndrome. Accessed Nov. 24, 2010.
6. Podrid PJ. Pharmacologic therapy of arrhythmias associated with the Wolff-Parkinson-White syndrome. http://www.uptodate.com/home/index.html. Accessed Nov. 24, 2010.
7. Knight BP. Nonpharmacologic therapy of arrhythmias associated with the Wolff-Parkinson-White syndrome. http://www.uptodate.com/home/index.html. Accessed Nov. 24, 2010.
8. Prevention & treatment of arrhythmia. American Heart Association. http://www.heart.org/HEARTORG/Conditions/Arrhythmia/PreventionTreatmentofArrhythmia/Prevention-Treatment-of-Arrhythmia_UCM_002026_Article.jsp. Accessed Nov. 24, 2010.
9. Symptoms, diagnosis & monitoring of arrhythmia. American Heart Association. http://www.heart.org/HEARTORG/Conditions/Arrhythmia/SymptomsDiagnosisMonitoringofArrhythmia/Symptoms-Diagnosis-Monitoring-of-Arrhythmia_UCM_002025_Article.jsp. Accessed Nov. 24, 2010.
10. Shen W-K (expert opinion). Mayo Clinic, Rochester, Minn. Dec. 14, 2010.
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